Mobile electronic device having a geographical position dependent light and method of and system for achieving the same

ABSTRACT

The present invention provides a method and system for controlling an illuminating device on a mobile electronic device comprising determining in a global position of the device in real-time, determining a state of at least one light condition currently affecting ambient light at the global position and adjusting the intensity of the illuminating device in response to the state of the at least one light condition. Light conditions include weather conditions and a position of the sun at a particular global position. A mobile electronic device having a geographically dependent illuminating device is also provided.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.11/045,073, filed Jan. 31, 2005.

FIELD OF THE INVENTION

This invention relates to the field of mobile electronic devices.Specifically, the invention relates to a method and system forcontrolling a light based on geographical positional data and acorresponding device having a position dependent light.

BACKGROUND OF THE INVENTION

Mobile electronic devices are becoming more and more ubiquitous becausethey help users manage their busy schedules, as well as communicate withthe world. For example, portable computers, such as notebook or laptopcomputers, personal data assistants (PDAs) and mobile telephones arebecoming necessities for many. Notebook or laptop computers are verypopular because they are extremely lightweight personal computers thatcan easily fit in a briefcase for the mobile businessperson. A PDA is ahandheld mobile device that allows users to access information, keeptrack of their busy schedules, and communicate with others. A typicalPDA can function as a mobile or cellular phone, fax sender, and personalorganizer. Furthermore, many PDAs are capable of wireless connectivity.It is very important for today's mobile professional to be able toaccess information from anywhere in the world. Similar to the portablecomputer, PDAs are very popular because they are designed to be highlyportable.

Positional systems have been recently incorporated into personalcomputers, electronic mobile devices and automobiles. For example, asdescribed in U.S. Pat. No. 5,528,248 to Steiner et al., entitled“Personal Digital Location Assistant Including a Memory Cartridge, A GPSSmart Antenna and a Personal Computing Device”

Real time positional systems often access positional data from varioussources, such as local transmitters or satellites. Real time positionalsystems include GPS (Global Position Satellites), MLS (Microwave LandingSystems), GSM (Global System Mobile), GIS (Geographical InformationSystems) and CPS (Cambridge Positioning Systems).

A typical GPS unit includes (along with other components), a GPSreceiver for receiving transmitted signals from a number of satellites,a memory in which cartographic data and other location information maybe stored, a processor and associated GPS software for determining thelocation of the unit as a function of the received satellite signals andfor accessing and processing data and information in the memory, andtypically a display for displaying the information along with anindication of the unit's location. The memory may be integral with theprocessor, memory chips coupled with the processor, may include plug-inmemory modules that fit within corresponding memory slots in thereceiver or may be accessed remotely via a network such as wirelesslythrough the Internet. The processor retrieves information from thememory, for example, to display maps and routing instructions to permita user of the GPS receiver to navigate to a desired location.

U.S. Pat. No. 6,778,837 to Bade et al. also incorporates GPSfunctionality into a PDA. Bade et al. describes a system and method forproviding access to mobile devices based on positional data. The methodinvolves predefining access parameters, determining the actual locationof the device and automatically controlling access to the device.

Aside from size, the principal difference between a notebook, PDA orlaptop computer and a personal computer is the display screen. Mobiledevices typically use flat-panel technologies, which are lightweight andnon-bulky. The primary function of a display screen is to provide aclear and readily viewable presentation to a user. One of the mostimportant factors affecting a user's ability to easily perceive theshapes or images of a presentation is sufficient illumination of thedisplay screen. Ambient light is often insufficient to provide adequateillumination of a display screen and a display screen usually includeslighting provisions such as a backlight. Since, providing too muchbacklight can also result in whiting out the screen, it is desirable toprovide backlights that are automatically controlled.

U.S. Pat. No. 6,812,649 to Kim provides a device and method forcontrolling LCD backlight. Kim teaches a backlight control device andmethod for reducing or minimizing the battery usage. Kim teachesoperating backlight control using intensity of detected surroundinglight within a selected control range from a plurality of backlightcontrol ranges. The backlight control ranges can vary in number but aredirected into various levels, according to the intensity of surroundinglight and use of a battery or an external power source.

SUMMARY OF THE INVENTION

According to one broad aspect of the invention, there is provided amethod for controlling an illuminating device on a mobile electronicdevice comprising, determining a global position of the device inreal-time, determining a state of at least one light condition currentlyaffecting ambient light at the global position and adjusting theintensity of the illuminating device in response to the state of the atleast one light condition.

Preferably, the intensity of the illuminating device is adjusteddynamically according to weather conditions and the position of the sunat the global position.

According to another aspect of the invention, there is provided a mobileelectronic device having an automatically controlled illuminating devicecomprising the illuminating device and a controller for determining acurrent global position of the device and adjusting the intensity of theilluminating device according to a state of at least one light conditioncurrently affecting ambient light at the global position. The controlleris coupled to communicate with (a) a receiver configured to receive datafrom a positioning system to determine the global position and (b) atleast one memory storing (i) data used to calculate the global positionbased on data from the positioning system and (ii) data relating tostates of at least one light condition at various global positions.

According to another aspect of the invention, there is provided a systemfor controlling an illuminating device on a mobile electronic devicecomprising the mobile electronic device, the illuminating device coupledto the device, a positioning system, a receiver coupled to the deviceand configured to receive data from a positioning system used todetermine a global position of the device, at least one memory forstoring data used to determine the global position and data relating tostates of at least one light condition at various global positions and acontroller coupled to the device and to communicate with the at leastone memory, for determining the global position of the device andadjusting the intensity of the illuminating device according to a stateof at least one light condition affecting ambient light at the globalposition.

According to another aspect of the invention, there is provided a datacarrier product containing sequences of instructions which when executedcauses the performance of the methods of the invention.

According to another aspect of the invention, there is provided asoftware product containing sequences of instructions which whenexecuted causes the performance of the methods of the invention.

According to another aspect of the invention, there is provided anintegrated circuit product containing sequences of instructions whichwhen executed causes the performance of the methods of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention may best be understood by referring to thefollowing description and accompanying drawings. In the description anddrawings, like numerals refer to like structures or processes. In thedrawings:

FIG. 1 is a flowchart illustrating operations for controlling abacklight for a display in a mobile electronic device according to afirst embodiment of the invention;

FIG. 2 is a flowchart illustrating operations for controlling abacklight for a display in a mobile electronic device according to asecond embodiment of the invention having dynamic control of theilluminating device;

FIG. 3 is a flowchart illustrating operations for controlling abacklight for a display in a mobile electronic device according toanother embodiment of the invention; and

FIG. 4 shows a mobile electronic device having a position dependentbacklight and an associated system.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the invention. However, it isunderstood that the invention may be practiced without these specificdetails. In other instances, well-known software, circuits, structuresand techniques have not been described or shown in detail in order notto obscure the invention.

Method. Generally, in accordance with an aspect of the invention, thereis provided methods for controlling a display backlight on a mobileelectronic device based on positional data. An electronic mobile devicemay include, but is not limited to, laptops, PDAs or mobile phones. Itwill also be understood by a person skilled in the art that a mobileelectronic device may also include devices that are resident on otherdevices that are mobile such as a navigational computer in a vehicle.Referring to FIG. 1, operations 100 for controlling a display backlightaccording to a broad embodiment of this aspect of the invention isprovided. At step 120, a real-time global position of the device isdetermined. Real-time global position can be determined using variouspositional systems, such as, for example, GPS (Global PositionSatellites), MLS (Microwave Landing Systems), GSM (Global SystemMobile), GIS (Geographical Information Systems) and CPS (CambridgePositioning Systems). Preferably, the GPS system is used. Typically, GPSinformation is transmitted to a receiver either in the device orexternal to the device but capable of communicating with the device. TheGPS information, along with cartographic data and other locationalinformation stored on a memory, is processed by a processor which thencalculates the real-time global position of the device according to GPSsoftware.

At step 130, a state of at least one light condition is determined basedon the real-time global position of the device. Light conditions caninclude any light condition that currently affects the ambient light atthe global position, including, but not limited to, current weatherconditions, lunar cycle and the position of the sun or moon (e.g.altitude and optionally azimuth) at that particular time of day.Therefore, with respect to weather condition, the state of the weathercondition at the global position may be sunny, cloudy, raining, snowing,. . . etc. These states may affect the ambient light at the globalposition. Similarly, the state of the position of the sun, particularlythe altitude, and optionally azimuth, of the sun relative to the globalposition, will vary depending on the current time and day. A backlightdependent on the position of the sun will be more accurate than merelyusing the time of day since sun rise and sun set times differ dependingon the global position and the time of year. For example, there can be24 hour daylight or darkness at the poles of the earth.

State of light conditions at various global positions may be stored andretrieved from a resident memory or an external memory via a network.Preferably, this light condition data is retrieved in real-timewirelessly. It will be understood by a person skilled in the art thatthe current state of a light condition at the global position may bedirectly retrieved (e.g. the current position of the sun at the globalposition), or alternatively, calculated using the current local time atthe global position and data regarding light conditions at various timesof the day (e.g. the position of the sun at the global position atvarious times of day). Local time at the global position may bedetermined by a clock on the device or preferably by retrieving localtime data according to the global position. Similarly local time datamay be stored and retrieved from a resident memory or an external memoryvia a network

At step 140, the backlight is adjusted according to the state of the atleast one light condition. Therefore, the intensity of the backlightwill be increased for example, if it is more overcast as opposed tosunny or dusk as opposed to noon. It will be understood by a person ofordinary skill that the backlight can also have only two states, on andoff, and adjusting the intensity of the backlight could comprisesturning the backlight on.

Referring to FIG. 2, a method for controlling the backlight of anelectronic mobile device according to another embodiment of theinvention is illustrated. In this preferred embodiment, the backlightcan be dynamically adjusted based on the global position of the device.Accordingly, with reference to FIG. 2, operations 200 include a furtherstep 210 is provided to operations 100 for looping back to step 120after step 140 to dynamically adjust the intensity of the backlightbased on global position. In this embodiment, the dynamic feature of themethod may be tuned on or off as represented by the decisional nature ofstep 210.

Referring to FIG. 3, operations 300 according to a preferred embodimentof the invention are provided. At step 310, a range of ambient lightvalues are predefined depending on a state of various light conditions,and more particularly, various weather conditions and a position of thesun relative to various global positions at particular times of the day.In respect of weather conditions, it is anticipated that the ambientlight value will change depending on states of the weather, such asthose described above, namely, the amount of cloud cover, rainconditions and/or snow conditions at that global position. In respect ofsun position, it is similarly anticipated that the ambient light valuewill change depending on states such as the particular time of day andthe altitude of the sun at that time, sun rise and sun set times. Asdiscussed above, this is more accurate than merely calculating anambient light value based on only the time of day since the altitude andpath of the sun differ depending on the global position and the time ofyear.

The predefined range of ambient light values represents the ambientlight at the global position and is therefore preferably dependent onthe combination of both weather condition and the position of the sun.For example, when the sun has already set for several hours, typicallythe middle of the night, there will be little ambient light (for thepurposes of viewing a display) despite the sky being relatively clearand this would be reflected in a low ambient light value. A personskilled in the art would understand that incorporating other lightconditions is also possible. For example, the fullness and position ofthe moon at a given global position on a clear night may also affect theamount of ambient light at a given geographical location. Therefore,information regarding the lunar cycle and the position of the moon canalso be incorporated into the predefined range of ambient light values.

At step 320, a range of backlight intensities are predefined based onthe range of ambient light values.

At step 330 the real-time global position of the device is calculatedsimilar to step 120 of method 100.

Once the global position of the device is determined, at step 340,actual current weather conditions at the global position are retrieved.At step 350, actual current position of the sun data is retrieved basedon the global position of the device. As discussed above in connectionwith method 100, weather condition data and position of the sun data maybe stored and retrieved from a resident memory or downloaded inreal-time from a network that is preferably wireless.

At step 360, an ambient light value is calculated based on actualweather conditions and position of the sun data at the global positionat the current time and according to the ranges of ambient light valuespredefined at step 310.

At step 370, backlight intensity is adjusted based on the ambient lightvalue and according to the ranges of backlight intensity predefined atstep 320.

Since light conditions, such as weather and the position of the sun,tend to have a greater effect on the ambient light at a global positionif the user is actually outdoors, operations 100, 200 or 300 may dependon an initial decision step (not shown) of turning the device into“outdoor” mode before proceeding to the remainder of the steps of theinvention.

According to another embodiment of the invention, the device canautomatically predict whether the device is outdoors or indoors. Forexample, such a prediction may be based on the global position andcomparing the outdoor temperature conditions at the global position tothe actual temperature as measured by a temperature sensor on thedevice.

Device and System. Referring to FIG. 4, a mobile electronic device 402having a global position controlled backlight is shown in a system 500.The mobile electronic device 402 is preferably a two-way communicationdevice having at least voice and advanced data communicationcapabilities, including the capability to communicate with othercomputer systems. Depending on the functionality provided by mobileelectronic device 402, it may be referred to as a data messaging device,a two-way pager, a cellular telephone with data messaging capabilities,a wireless Internet appliance, or a data communication device (with orwithout telephony capabilities). Mobile electronic device 402 maycommunicate via a network 400, in this embodiment, any one of aplurality of fixed transceiver stations within its geographic coveragearea.

Mobile electronic device 402 will normally incorporate a communicationsubsystem 411, which includes a receiver, a transmitter, and associatedcomponents, such as one or more (preferably embedded or internal)antenna elements and, local oscillators (LOs), and a processing modulesuch as a digital signal processor (DSP) (all not shown). Communicationsubsystem 411. As will be apparent to those skilled in field ofcommunications, particular design of communication subsystem 411 dependson the communication network in which mobile electronic device 402 isintended to operate. In this embodiment of the invention communicationsubsystem 411 includes a receiver configured to receive data from apositioning system 470 to accurately determine the global position ofmobile electronic device 402.

Network access is associated with a subscriber or user of mobileelectronic device 402 and therefore mobile electronic device 402requires a Subscriber Identity Module or “SIM” card 462 to be insertedin a SIM IF 464 in order to operate in the network. Mobile electronicdevice 202 is a battery-powered device so it also includes a battery IF454 for receiving one or more rechargeable batteries 456. Such a battery456 provides electrical power to most if not all electrical circuitry inmobile electronic device 402, and battery IF 454 provides for amechanical and electrical connection for it. The battery IF 454 iscoupled to a regulator (not shown) which provides power V+ to all of thecircuitry.

Mobile electronic device 402 includes a controller such as amicroprocessor 438 which controls overall operation of mobile electronicdevice 402. Communication functions, including at least data and voicecommunications, are performed through communication subsystem 411.Microprocessor 438 also interacts with additional device subsystems suchas a display 422, a backlight 423 for illuminating display 422, a flashmemory 424, a random access memory (RAM) 426, auxiliary input/output(I/O) subsystems 428, a serial port 430, a keyboard 432, a speaker 434,a microphone 436, a short-range communications subsystem 440, and anyother device subsystems generally designated at 442. Microprocessor isalso capable of adjusting the intensity of backlight 420 according to astate of at least one light condition affecting ambient light at theglobal position of the device. Some of the subsystems shown in FIG. 4perform communication-related functions, whereas other subsystems mayprovide “resident” or on-device functions. Notably, some subsystems,such as keyboard 432 and display 422, for example, may be used for bothcommunication-related functions, such as entering a text message fortransmission over a communication network, and device-resident functionssuch as a calculator or task list. Operating system software used bymicroprocessor 438 is preferably stored in a persistent store such asflash memory 424, which may alternatively be a read-only memory (ROM) orsimilar storage element (not shown). Those skilled in the art willappreciate that the operating system, specific device applications, orparts thereof, may be temporarily loaded into a volatile store such asRAM 426.

Microprocessor 438, in addition to its operating system functions,preferably enables execution of software applications on mobileelectronic device 402. A predetermined set of applications which controlbasic device operations, including at least data and voice communicationapplications, will normally be installed on mobile electronic device 402during its manufacture. A preferred application that may be loaded ontomobile electronic device 402 may be a personal information manager (PIM)application having the ability to organize and manage data itemsrelating to the user such as, but not limited to, instant messaging(IM), e-mail, calendar events, voice mails, appointments, and taskitems. Naturally, one or more memory stores are available on mobileelectronic device 402 and SIM 462 to facilitate storage of PIM dataitems and other information.

The PIM application preferably has the ability to send and receive dataitems via the wireless network. In a preferred embodiment, PIM dataitems are seamlessly integrated, synchronized, and updated via thewireless network, with the mobile electronic device user's correspondingdata items stored and/or associated with a host computer system therebycreating a mirrored host computer on mobile electronic device 402 withrespect to such items. This is especially advantageous where the hostcomputer system is the mobile electronic device user's office computersystem. Additional applications may also be loaded onto mobileelectronic device 402 through network 400, an auxiliary I/O subsystem428, serial port 430, short-range communications subsystem 440, or anyother suitable subsystem 442, and installed by a user in RAM 426 orpreferably a non-volatile store (not shown) for execution bymicroprocessor 438. Such flexibility in application installationincreases the functionality of mobile electronic device 402 and mayprovide enhanced on-device functions, communication-related functions,or both. For example, secure communication applications may enableelectronic commerce functions and other such financial transactions tobe performed using mobile electronic device 402.

In a data communication mode, a received signal such as a text message,an e-mail message, or web page download will be processed bycommunication subsystem 411 and input to microprocessor 438.Microprocessor 438 will preferably further process the signal for outputto display 422, to auxiliary I/O device 428 or both. A user of mobileelectronic device 402 may also compose data items, such as e-mailmessages, for example, using keyboard 432 in conjunction with display422 and possibly auxiliary I/O device 428. Keyboard 432 is preferably atelephone type keypad, full alphanumeric keyboard or full or condensedQWERTY keypad. These composed items may be transmitted over acommunication network through communication subsystem 411.

For voice communications, the overall operation of mobile electronicdevice 402 is substantially similar, except that the received signalswould be output to speaker 434 and signals for transmission would begenerated by microphone 436. Alternative voice or audio I/O subsystems,such as a voice message recording subsystem, may also be implemented onmobile electronic device 402. Although voice or audio signal output ispreferably accomplished primarily through speaker 434, display 422 mayalso be used to provide an indication of the identity of a callingparty, duration of a voice call, or other voice call relatedinformation, as some examples.

Serial port 430 in FIG. 4 is normally implemented in a personal digitalassistant (PDA)-type communication device for which synchronization witha user's desktop computer is a desirable, albeit optional, component.Serial port 430 enables a user to set preferences through an externaldevice or software application and extends the capabilities of mobileelectronic device 402 by providing for information or software downloadsto mobile electronic device 402 other than through a wirelesscommunication network. The alternate download path may, for example, beused to load an encryption key onto mobile electronic device 402 througha direct and thus reliable and trusted connection to thereby providesecure device communication.

Short-range communications subsystem 440 of FIG. 4 is an additionaloptional component which provides for communication between mobileelectronic device 402 and different systems or devices, which need notnecessarily be similar devices. For example, subsystem 240 may includean infrared device and associated circuits and components, or aBluetooth™ communication module to provide for communication withsimilarly-enabled systems and devices. Bluetooth™ is a registeredtrademark of Bluetooth SIG, Inc.

In accordance with an embodiment of the invention, mobile electronicdevice 402 is configured for sending and receiving data items andincludes a PIM for organizing and managing data items relating to theuser such as, but not limited to, instant messaging (IM), e-mail,calendar events, calendar appointments, and task items, etc. By way ofexample, mobile electronic device 402 is configured for voice (which mayinclude push to talk over cellular (POC)) and data services, voice mailservice, e-mail service, SMS and chat services to which the usersubscribes. To provide a user-friendly environment to control theoperation of mobile electronic device 402, PIM together with theoperation system and various software applications resident on thestation 402 provides a GUI having a main screen from which to accessvarious services via applications stored on said device or available toit.

In operation, communication subsystem 411 housing a positioning systemreceiver receives data transmitted from positioning system 470. Alongwith cartographic and locational data contained on flash memory 424,this positional data is processed by microprocessor 438 to determine aglobal position of mobile electronic device 402. Alternatively,including the global positions systems previously described, a generalglobal position may be determined with reference to a local base stationor other network 400 component with which device 402 is thencommunicating.

The state of various light conditions is then determined bymicroprocessor 438 based on the global position. Data regarding lightconditions, such as whether conditions and position of the sun, can bedownloaded to mobile electronic device 402 ahead of time and retrievedfrom flash memory 424 or preferably, retrieved real-time from an outsidememory 480, such as a server, via network 400. It will also beunderstood by a person skilled in the art that the cartographic andlocational data used to calculate global position, as may be necessary,may similarly be stored on and retrieved from outside memory 480 as analternative to flash memory 424.

Microprocessor 438 then adjusts the intensity of backlight 423 accordingto the state of various light conditions. Adjustment may be as simple asturning the light on or off.

Although operations 100, 200 and 300, system 500 and device 402 havebeen described with respect to a backlight for a display on a mobileelectronic device, it will be understood by a person skilled in the artthat any light or illuminating device on a mobile electronic device maybe controlled in this manner. For example, intensity of lights thatilluminate a keypad or keyboard or of the display itself (eg. thebrightness of an LCD display) may all be controlled in a geographicalposition dependent manner. Any lights associated with vehicles, such as,for example, headlights, dashboard lights, and electronic displaysinside the vehicle may also be controlled in this manner.

Data Carrier Product. The sequences of instructions which when executedcause the methods described herein to be performed by system 500 can becontained in a data carrier product for transmission such as embodied ina carrier wave according to one embodiment of the invention.

Computer Software Product. The sequences of instructions which whenexecuted cause the methods described herein to be performed by system500 can be contained in a computer software product according to oneembodiment of the invention. This computer software product can beloaded into and run by system 500.

Integrated Circuit Product. The sequences of instructions which whenexecuted cause the methods described herein to be performed by system500 can be contained in an integrated circuit product including acoprocessor or memory according to one embodiment of the invention. Thisintegrated circuit product can be installed in system 500.

Although preferred embodiments of the invention have been describedherein, it will be understood by those skilled in the art thatvariations may be made thereto without departing from the spirit of theinvention or the scope of the appended claims.

1. A method for controlling backlighting of a display on a mobileelectronic device, the method comprising steps of: determining a currentglobal position of the device; retrieving current weather conditions forthe current global position by downloading weather condition datathrough a wireless network; predicting ambient light for the currentglobal position of the device based on a time of day, a time of year andthe current weather conditions at the current global position of thedevice; and dynamically adjusting the backlighting of the display inresponse to changes in the predicted ambient light.
 2. The methodaccording to claim 1, wherein determining the current global position ofthe device comprises using a global positioning system.
 3. The methodaccording to claim 1, wherein the step of retrieving the current weatherconditions for the current global position comprises wirelesslyaccessing weather condition data stored in memory residing on a serverconnected to the mobile device via said wireless network.
 4. The methodaccording to claim 1, comprising the step of enabling a user topredefine a range of backlighting intensities corresponding to apredefined ambient light conditions.
 5. The method according to claim 1,comprising the step of enabling a user to select an outdoor mode for thedevice.
 6. The method according to claim 1, comprising the step ofpredicting whether the device is outdoors or indoors by comparingoutdoor temperature conditions at the current global position of thedevice to an actual temperature measured by a temperature sensor on thedevice.
 7. A mobile electronic device having automatically controlledbacklighting, the device comprising: a backlit display having adjustablebacklighting; a means for determining a current global position of thedevice; a means for retrieving current weather conditions for thecurrent global position of the device by downloading weather conditiondata through a wireless network; and a microprocessor for dynamicallyadjusting the backlighting of the backlit display in response to ambientlight conditions that are predicted based on a time of day, a time ofyear, and the current weather conditions for the current global positionof the device.
 8. The device of claim 7, wherein the means fordetermining the current global position of the device is a globalpositioning system.
 9. The device of claim 7, wherein the means forretrieving current weather conditions for the current global positioncomprises a wireless data connection via said wireless network to aserver that stores global weather data.
 10. A system for automaticallycontrolling backlighting on a mobile electronic device connected to awireless network, the system comprising: a positioning system fordetermining a current global position of the device; a server forstoring data relating to current weather conditions prevailing atvarious global positions; and a wireless link connecting the mobileelectronic device to the server for enabling the mobile device todownload weather condition data through a wireless network for anambient light condition for the current global position for providing toa microprocessor of the mobile device which is configured to dynamicallyadjust the backlighting of the display in response to ambient lightconditions that are predicted based on a time of day, a time of year,and the current weather conditions for the current global position ofthe device.
 11. The system of claim 10 wherein the positioning system isa global positioning system.
 12. A computer program embodied on acomputer readable medium comprising computer readable program code meansadapted to perform all of the steps of the method of claim 1 when saidprogram is run on a computer.